HR: 0830h
AN: U51B-0014    [PDF]
TI: High-Pressure Melting of Mg-Perovskite and its Assemblage With Periclase From Shock Temperature Measurement
AU: * Luo, S
EM: sluo@lanl.gov
AF: Plasma Physics P-24, Los Alamos National Laboratory, MS E526, Los Alamos, NM 87545 United States
AU: * Luo, S
EM: sluo@lanl.gov
AF: Seismological Laboratory, California Institute of Technology, MC 252-21, Pasadena, CA 91125
AU: Akins, J A
EM: jakins@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, MC 252-21, Pasadena, CA 91125
AU: Ahrens, T J
EM: tja@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, MC 252-21, Pasadena, CA 91125
AU: Asimow, P D
EM: asimow@gps.caltech.edu
AF: Division of Geological & Planetary Sciences, California Institute of Technology, 170-25, Pasadena, CA 91125 United States
AB: Optical emission of MgSiO$_3$ glass, enstatite and olivine under shock wave compression were investigated with optical pyrometry at discrete wavelengths ranging from visible to near infrared. At individual wavelengths, the optical linear absorption coefficients ($a$) and black-body spectral radiances ($L_{\lambda b}$) of shocked and unshocked materials were obtained by non-linear fitting to the time-resolved radiance from the target assembly. The absorbtion spectra of unshocked samples corresponding to the measured values of $a$ reproduce those from independent static optical spectroscopic measurements. The measured values of $a$ for shocked samples indicate that shock-induced high-pressure phases (including melt) can be regarded essentially as black body in the optical range investigated, although starting phases such as enstatite and olivine have band-like spectra at ambient conditions. High-pressure melting curves of Mg-perovskite and its assemblage with periclase are deduced with their melting temperatures near the core-mantle boundary being $6000\pm500$ K and $4200\pm300$ K, respectively.
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3944 Shock wave experiments
DE: 8124 Earth's interior--composition and state (old 8105)
SC: U
MN: 2003 Fall Meeting